Rheostat and potentiometer



Sep 1930- v 4 w. A. BRUNO I 7 RHEOSTAT AND POTENTIOIETBR Filed March 22.1929 INVENTOR VVZZZiam lLl'n-zmo ATTORNEYS secured to a tubular member.rate the ring to Patented Sept. 16, 1930 UNITED STATES PATENT OFFICEWILLIAM A. BRUNO, on NEW YORK, N. Y., AssreNon' 'ro cnaaos'ra'r ure. co.me, or BROOKLYN, NEW YORK, A CORPORATION on NEW YORK RHEOSTAT ANDPOTENTIOMETEB Application filed larch 22, 1929. Serial No. 349,087.

This invention relates to an improved rheostat and potentiometer, andhas for an object to provide a construction wherein the contacting partsmay be quickly, accurately varied without a scraping action of thecontacting members.

Another object of the invention is to provide a device which may act asa rheostat or as a potentiometer, the structure including a gyratorycontact ring with means for causing the ring to function as the controlknob is rotated. I

.A further object, more specifically, is to provide a combined rheostatand potentiometer wherein a desired resistance coacts .with a gyratingring controlled by cams operated by a control knob, so that as the knobis rotated the cams will swing or gyproduce a desired shifting of theconnections while maintaining a pressure contact rather thana slidingcontact.

In the accompanying drawings Figure 1 is a rear view of'the constructionembodying the invention;

Figure 2 is an edge view of the structure shown in Figure 1;

Figure 3 is a sectional view through Figure 1 on the line 3-3;

Figure 4 is a sectional view through Figure 3 approximately on line 44;

Figure 5 is a plan view of one of the cams shown in Figure'3;

Figure 6 is a plan view of the contact ring shown in Figure 3.

Referrin to the accompanying drawings numera s, 1 indicates a wire woundreslstance of a desired kind secured to a suitable supporting casing 2but insulated therefrom b a. suitable lnsulatin member 3. It will eunderstood that, alt ough a wire wound resistance is shown in thedrawing, other forms of resistances may be used and the term resistancein the specification is intended to cover these other forms, as forinstance, compressed carbon or carbon impregnated paper. The casing 2 isI'lgldl 4 throug which the shaft or rod 5 extends. This shaft rotatesinorder to secure a desired adjustment of the various parts and may beeasily and 'tacts with the resistance "but the point of contactmanipulated by any desired means, as, for instance, a suitable knob 6.Heretofore in most rheostats and potentiometers-a sliding contact wasprovided and positioned to coact with the resistance 1. Usually thissliding contact was connected with a shaft similar to shaft 5 and causedto move over the resistance to secure the desired adjustment. In thepresent instance a gyrating ring 7 is provided. This ring is ofcomparatively stifl' metal but is somewhat resilient so as to provide aresilient, tight contact when properly brought into engagement with anypart of the resistance 1. As shown in Figure 6, ring? is provided withan outer annular portion merging into a plurality of spokes 8 which inturn merge into a central disk or plate 9. Normall the plane of theplate 9 is parallel with the plane of the ring 7 but Mug 7 is usuallyslightly distorted when in use, as shown in eflicient contact withcured. As shown in the resistance 1 is se- Fig. 3, the ring 7 con- 1 atpoint 10. By contact point will gyrating action of scraping or slidingrotating the shaft 5 this be shifted by a rolling or ring 7. There willbe no movement between ring of the ring with resistance 1 will be veryintimate and firm, so that the current may pro erly flow in the desirednew path. Ring does not rot-ate but the different points around the ringmerely move toward or from resistance 1, as shaft 5 rotates. Y This isbrought about by the cams 11 and 12 acting on plate 9. A stop 13 extendsloosely through an aperture 14 1n one of thearms 8 so as to prevent anyaccidental rotary movement of ring 7 s and also to provide an abutmentfor the arm 15, which arm is'provided with a stop projec tion 16 andwith a substantially rectangular- Figure 3; whereby an 7 and resistance1,.

' therefore be seen that the cams 11 and 12,

when assembled in the unit opposite to each other, form an inclined;opening .by virtue of the inclined surfaces, and into this openingrocker 7 is loosely placed so that by 'rotatin the shaft 5 a rocking orgyrating'movemen of the cams is imparted to member 7. The

arm 15 is preferably an integral part of adisk '22 which snugly fits thesection 18 soas to rotate therewith and strike the arm 13' from whichprojectibn 13 extends.

[the shaft 5 to have almost a complete revolution and thereby cause thecams to rotate the same distance, in order that the ring 7 shallfunction throughout the wound portion Of the resistance 1. The ends -ofthe resistance 1 are connected to the terminals 23 and 24, while thecasing 2 through theuse of clamping members 26. When these threeterminals are I used the device will be functioning as a po-.tentionmeter, whereas when only two are varying the width of portion 15of stop 22 the E ection .16is enga preciable wearing of the resistance.

used the device will function as a rheostat. Preferably the parts are soformed that by r1ng7 may or may not be in contact with any art ofresistance 1' when the arm 15 or prog arm 13. By forming the parts asdescrlbed and causing the ring 7 to move toward andfrom 'the resistance1 insteadlof sliding thereover will result in a very efiicient contactand will prevent ap- By providing an arm'which slides over the resistorthe wearing action-is-considerable, as the arm must pressagainst'theresistor in order to secure the desired contact. Thisfriction or wearing'action will soon wear the resistor or resistanceuntil the instrument will be of no appreciable value. By causing thecontact ring 7 to move toward and from the resistor the contact is not asliding one but has the effect merely of the resistor and ten'pulling'the object directly therefrom. This form of contactpractically eliminates wear byv reason of theabsence of any appreciablefriction. By the rocking or rolling action of the ring 7 a va-' riablecontact with the surface of the resistor is secured. This rollingaction, instead of a sliding or rubbing action, obviates any abrasion ofthe resistor, while at the same time there is secured a way. theresistance etween the contact element and the end of the terminals ofthe resistor may be controllably varied.

It will be understood that the device may be mounted in any desiredmanner and conby having the end 21 upset. It will This permits wardly inorder to pro terminal 25 .is grounded on the portions of the resistance,

ushing an object against.

groper contact. In this In the accompanying drawings a certain form ofcam has been disclosed, and infact,

opposing cams have been presented having an inclined openingtherebetween, whereby the ring 7 may be tilted. It is evident that otherspecific forms of cams may be used without departing from the spirit ofthe invention, provided this inclined opening and the action of the camsare maintained. Instead of having cams formed separately from the shaftthey could be made an integral part thereof. The two cams are used inorder to have a positive up and down movement as the shaft rotates, butif the up er cam is removed a sprin could be substituted so that theaction, so ar as the ring 7 is concerned, will be the same. Where thecam is produced by an inclinedannular groove on the shaft the platesurrounding the shaft would have a slot extending from the peripheryinerly center the ring 7 and cause the parts to notion properly. What Iclaimis':--

1. A device of the character. described, in

. cluding a substantially annular resistance, an annular ring coactingtherewith, a pair of rotating cams for shifting-the ring to producearocking action to brlng successive portions of the ring into contactwith successive and arotatable member for causing said cams to function.

2. A. device of the character described, comprisinga casing, aresistance carried by said casing, said resistance being substantiallyannular, astop carried by the casing,

a, ring member coactmg with said resistance and provided with a centralplate and radiating arms, one of said arms having an aperture throughwhich said stop loosel projects, a cam contacting with each side 0 saidcentral plate, a rotatable shaft rigidly connected with said cams forrotating the cams, whereby the ring member will be given an oscillatorymotion and this motion will cause the outer part of the ring member tohave successive portions thereof brou ht into contact with successiveportions 0 said resistance, and an arm connected with said rotatableshaft formed with means positionedto strike saidstop, whereby saidrotatable shaft can be rotated slightly less than a complete revoluion.I r

3. A device of the character described, including a'substantiallyannular resistance, a ring member having a central plate and aperipheral contact portion adapted to engage said resistance, an annularcam arran ed in contact with each face of said plate, sai cams being setin 0 position so that when the are rotated simu taneously the plate wibe rocked to cause said peripheral contact portion to bring successivedifferent ortions thereof into contact with successive 'iferent portionsof said resistance, and a rotatable shaft coacting with said cams foractuating the cams. 4. A device of the character described, in- 5eluding a substantially annular resistance, means acting as terminals tosaid resistance, an annular member coacting with said resistance, and apair of oppositely acting cams positioned to rock said annular memberwhen the cams are rotated, said annular member being positioned betweenand in contact with .J said cams whereby the annular member will have arocking action in respect to the resistance for forcing successivedifferent portions into contact with successive difierent portions ofsaid resistance.

WILLIAM A. BRUNO.

